Building block element of a toy building set



FIG. 1 is a top perspective view of the building block element of a toybuilding set of my ornamental design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The ornamental design for a building block element of a toy buildingset, as shown and described.